1. Field of the Invention
The present invention relates to a white-light emitting electroluminescent display and a fabricating method thereof, and in particular to an improved white-light emitting electroluminescent display and a fabricating method thereof capable of emitting a light having a red, blue, and green wavelengths in a single light-emitting material and having a buffer layer of Si.sub.x N.sub.y between a lower dielectric layer of BaTa.sub.2 O.sub.6 and a light-emitting layer.
2. Description of the Conventional Art
Studies on a small-sized and thin-type flat panel display device having lightness have been widely conducted in the industry for use in a high definition television which requires a high resolution.
Among the above described small-sized and thin-type flat panel display devices, an electroluminescent display (hereinafter called the "ELD") which is a kind of a solid device, was introduced, which well works under a special working environment in which vibrations, impacts, and temperature changes take place.
The ELD is named because it has an light-emitting layer between two electrodes when an alternating current is applied to the two electrodes. Here, to enable the above described ELD to emit colorful lights, three different kinds of ELD emitting material and an emitting thin film fabrication method should be developed in advance. As a result, a red- and green-lights emitting ELD material were developed and had been used in the industry; however, there are some problems in fabricating a blue-light emitting ELD material and in developing a thin film-type ELD.
In another method of fabricating a full color emitting ELD, a method of providing full color ELD according to the "color by white" concept is the simplest method for achieving a multi- or full-color display. That is, it is directed to fabricate an ELD capable of emitting a red, blue, and green lights using a single white-light emitting layer and a thin film using a single host material and a single light-emitting center.
In this case, the conventional ELD includes a substrate, a lower electrode formed on the substrate, a lower dielectric layer formed on the lower electric layer, a light-emitting layer formed on the lower dielectric layer, a upper dielectric layer formed on the light-emitting layer, and an upper electrode formed on the upper dielectric layer. Here, an alternating current is applied between the upper electrode and the lower electrode.
To enhance the performance of the conventional ELD, the emitting material and dielectric layer material are very important.
The conventional white-light emitting ELD which was developed by using a single light-emitting layer has been developed using materials of ZnS:Pr, SrS:Pr, and SrS:Eu,Ce,K. An electroluminescent display of an SrS:Pr emitting layer using a single emitting center of Pr has an emitting level of 50 cd/m.sup.2.
In the industry, SiO.sub.x N.sub.y, Ta.sub.2 O.sub.5, TiO.sub.2, and Al.sub.2 O.sub.3 are commonly used as the materials of a dielectric layer.
In case of using an SiN.sub.x, since the dielectric constant of a dielectric layer is 4 to 6, which is relatively low, an emitting threshold voltage disadvantageously increases due to the voltage drop caused by a dielectric layer when electric power is applied thereto.
Meanwhile, in case of an ELD having a single dielectric film of Ta.sub.2 O.sub.5, since a dielectric constant is 25 to 29, which is relatively high, the level of the voltage decrease caused by the dielectric layer is reduced. As a result, the threshold voltage is advantageously decreased; however, the threshold voltage varies, and a threshold voltage characteristic degrades due to a leaky characteristic of a Ta.sub.2 O.sub.5 as an operation time lapses.